Game module could not be loaded after upgrading to 5.1

Hi, i got this error in attempt to upgrade the project to 5.1.

All i did was create a new UE5 project. Then i copied the source code from 4.27 project. Fixed all errors and dependencies, included the needed plugins too, so that i can build successfully. But somehow this error still existed and i can’t open the editor. But then i removed the source files, it worked and i can open the editor.

I still confused and have no idea how it’s still cannot open the game module, while there are no error left in the IDE and it can’t compile.

Anyone can help? Thanks in advance!